Device for preventing backflow in liquid-carrying lines



c. w. HOLTMAN Aug. 3, '1943.

DEVICE FOR PREVENTING BACK FLOW IN LIQUID CARRYING LINES Filed Dec. 6, 1939 Patented Aug. 3, 1943 ,nEvI oEronPnEvENTmGBACKFLOW1N' 1 im In-oARRYINGnINns h Clemens W. Hottman, Louisville; Ky., assignor'to American Radiator & Standard Sanitary Corporation-,a corporation ofi Delaware v Applicatiofi l jecember 6,1939, ScriaLNo. 307313 4 Claims gar en-69w Y The present invention relates to controldevices adapted to be inserted in a liquid-carrying line or pipe on the discharge side of a'con'trol' fixture such as a faucet or valve and between such and a sanitary fixture; to prevent afliack' flcw from such sanitary fixture into suohline or pipe.

For sanitary and other reasons, it is necessary to provide some means to prevent back flow or flow reversal from sanitary fixtures into service or supply water lines. For example, sinks and water closets are'frequently connected into the same water line, and means must.,b e provided which would prevent any possibility that the flow of water to the sink will be contaminated; :Likewise, in other connections it is often desirable to preclude undesirable admixture or contamside in the various structural combinations, sub combinations and details hereinafter described and claimediandin such other andjfurther matters as will be understood ,b y those slgill edin this art. An optional feature fofthe invention in cludes. the provision of meansioi breaking. a

vacuum which may form i the supply line under some conditions, I

In the accompanying drawingiwherein h ye illustra'tedone operative embodiment oi l thje V 7 present invention:

ination' of liquids in supply and. service lines and here too the necessity for a simple; dependable device is apparent. This is-particularlytme in connection with hospital .ffixtures to which this invention is'directed. While backffiow preventers, so-called, are known and presumably used to some extent, such have not generally been V V thoroughly dependable under all conditions of operation, particularly when the water supply is under very low pressure, when the supply valve is'only'partially openedflor when certain backpressure conditionsjprevail along with partial supply valve opening or low supplypressures,

nndrwhich ,circmnstances' spillageof water through the air port has been possible. 7

One of the objects of 'the present inventioniis ,to provide adevice for preventing back flow in water service and supply lines which is simple i andhighlyjeflective'under all anticipated conditions'of operationoruse 7 .i V Another object oftheinvention resides in'the provision. of a device which can jlbe interposed. on the discharge sideofany valve,'-dischargel or control fixture inawa'ter *or other supply or service'line, which is not subject to' deterioration 'from' corrosion and other" detrimental agencies and which can be repaired or replaced when necessary at minimumfexpense and with Figure 1 isa vertical "mediall seotion'gi iew", taken through a devicere'snonding'to the prsent i v n o 'Figlla a fragmentary view si nilar to Fig. l of aimodifiedfloat assembly; f jFi'g. 2 is a plan vie 'of thejbody member of Fig. 3 is a fragmentary 1secticnal view'of the .body member alone modified foryacuuln break i p r o sa' v f ,c f

Fig eis aview at. 90 to Fig. 1; partly in sec-j tion and partly in elevation, line,IV-IV of Fig.1;

, Figg5 is in part a perspective and in thief sectional view of the lower ortion of thepreent devicefand taken substantiallyonjline V.V Figsland iyfl Fig. 6 is afperspective view fof the ,bOtt' non-metallic float employedin the device of a present invention; a 7 V Fig. '7 is :a bottom; view of,the 11 Jat. of L 81qis aperspective view of assent with the float ofFig. 5', and", .Figq9 is a sectional view of jthle' 'fioat disc ofFig'am,

Similar numerals desig nalte 5 i throughout the various views .Ofithe draw:

parts mg. l e Referring to the drawing,; it will be apparent that the present device includes ajgenerallyjhol low and. more or less cylindrical body .m'emb I; The construction is such as, to providejja" I float chamber Hfin the iipper portion of the body whichv is adapted to receive the float assem bly hereinafter described. Interiorly, jthe' upper end .oi the fioat chamber is 'provided with lthreads l2 which'are adaptedto receive the cap assem+ j bly hereinafter described. H

Centrally located in the mm 15 or their):

per-portion of the body member, 1. ,e.,'ithe bottom' V of the float, chamber )l l, and {communicating by the annular, upstanding flange ,l5 'which rises from the bottom l3 aforesaid."Thisopening M t V and ita'keno'n the v sion l8.

- forms a closure.

communicates with a chamber 1 6 therebelow and laterally communicating with and forming an extension of the last chamber is an inlet opening H, formed in the lateral hollow body BXtell- This body extension flares outwardly, as shown, so that opening I! is larger than chamber l6 and is exteriorly threaded at IQ for the reception of a swivel nut which is interiorly threaded at'-2l, as shown. A. swivel 22 cooperates with the body extension 18 and the swivel nut 20, as shown, and is of generally circular or'v i cylindrical construction provided with. an external annular projection 23 which cooperates with the inturned terminal flange 24 of the swivel nut 20. The swivel is hollow, being provided with an interiorly threaded passageway 25 which merges into the reduced bore 25 at the inner end thereof, this reduced bore communicating-with the chamber Hi. It will be clear that the str'um ture just described enables the present device to be connected into a suitableliquid-carrying line such as a water service or supply pipe but is only intended to. illustrate one means of making such the upper portion of member l5 projects.

downwardly. Shank extension 44 works in aperture 21b as the float moves and prevents misalignment or disassembly of the parts, thus ensuring proper operation at all times.

The float assembly is completed by a bot-tom disc 48. This disc has spaced radial projections 43 similar to'those (41) described in connection with float 3T5 Disc 48is provided With an annular depending flange or skirt 46 so that the underside thereof presents a chamber 50 into which The underside 5| ofdisc 48 rests upon member l5 and thisiconstitutes the lowermost position of disc 48 onthe upper side of which the lower edge of float3'l rests,. as shown best in Fig. 1, forming in effect a bottomfor said float adapted to aca connection. The inventionfis notin any way limited to this connection. f g

The cap assembly hereinabove referred to inf cludes a centrally ported cap 2? which has an exteriorly threaded depending skirt or flange 28 adapted to engage the interior threads l2in the upper end of the body It). Intermediate this depending flan'ge 28 and the thickened marginal annulus 29 of the cap an inverted annular groove 30 is provided in which is disposed a suitable annular washer 3| composed of appropriate material, such as rubber. This Washer, plus the threaded engagement of the. cap with the body member providesa fluid-tight joint or connection. An annular valve seat 28a depends,. as shown, from the under side oftthe cap. The cap 21 is provided with a concavo-convex shield member 32. This shield member is maintained over the cap 21, and somewhat spaced vertically therefrom, and rests upon the apertured bearing 33 'which forms the center of a bowed or semielliptic member 34 rising from the cap, on either side of the central opening 35 thereof.. Ashield screw 36 passes through shield 32 and into bearing 33, thereby maintaining these. members in operative assembly. A bridge member 21c extends diametrically across opening35 andjlias an aperture 21b therein for a purposeto beiex plained. .j i

Disposed within the float chamber III is afloat assembly which includes a float proper 31.1 This lsa bottomless cylinder having a top 38' which 43 and thence into thethickened portion aforesaid, The fastening member 4! is preferably provided with a smooth'shank extension 44 superjacent the flange 45 the upper end of which The lower end of the cylinder extends into aperture 21!) of bridge member 27o.

The flange 45 serves'asa washer and snugly engages seat washer 43 as shown. The. float is provided externally with spaced vertical projecting ribs 4'! which maintain these-me properly centered in thefloat chamber and provide a com: munijcating passage from the air port to the fluid ports in the lower' part of therflcat chamber between the float and the float chamber wallfand avoid. jamming when the floatmoves upwardly or tuate the same upwardly when the buoyancy of the jet passing through inlet opening I4 is adequate so'ito do. This will be more fully understood in connection with the subsequent description of the operation of the device.

Attention is directed to the relatively high inlet seat due to the height of flange l5 and to the use of a skirted float disc. These constitute important and valuable featuresv of my invention. The arrangement noted modifies the turbulence characteristics of the device and makes it practically impossible for the air normally-trapped within the float to be aspirated even under' highly unusual conditions. Any displacement of such air by liquid would correspondingly reduce the buoyancy of the float temporarily and to that extent would impair the operation of the device. When constructed in accordance with my inven tion the air port 35Jis always sealed or closed prior to a rise of liquid to a level high enough to permit it to flow 'outthrough' such air port; hence, leakage atvthis point is impossible.

Both the float 31 and the float disc 48 are preferably made of Bakelite or from other non-metallic or resinous material but may be composed of any suitable material resistant to corrosion and light enough to respond to. conditionsas herein'set forth. The other portions of the device are preferably composed of a suitable metal or alloy such as brass, althou,gh it is to beunderstood that the particular composition of any part of the present device is'notintended to con'stitute alimitation' upon this invention, as,' any material may be employed which is satisfactory for'any particular use duefregard being given to the nature of the fluids'to contactwithwhich thedevice'maybe subjected. f

The trough-like portion 52 in the bottom. l3

of the float chamber I! is also provided with one or more outlet openings 53, two diametrically carrying line. As illustrated, the outlet extension 55 is in alignment with the float chamber and, is V internally threaded at56 to adapt it for engagement with the line mentioned. Lying between outlet extension 55 and the chamber l6 is'a partition wall 51 which forms the bottom of cham- 'ber l6 and maintains the inlet and outlet passageways separate and distinct. The device when installed is disposed so that it is positioned above thehighest level that liquid can' attain the liquid will alWa-ysb-in the directionaway from the device and toward the fixtur'e' I I While the present device is primarily designs to prevent back'flow under all possible contin gencies, it is also adapted by slight modification to act as a vacuum breaker. Such an arrange- 1mm is illustrated in Fig. 3 wherein it will apassociated fixture so that any gravityfiow 50f pear'that the upperedge of the flange (which j constitutes ani'nletseat) is provided with small angularl}; spaced (e. g., 99 apart) grooves I5",

this form' ot theinvention being otherwise the -same asFig.1 as willbe noted by the use of similar numeren but with a prime r) suffix. The K spaces represented by the grooves i5 'iorm aft controlled'leak between float chamber ii and 'the supply of liquid. Therefore, when negativev pressures arise or existin the supply line air is drawn back into the supply to break the vacuum but at such a rate as Will be commensurate with -maintaining substantially atmospheric pressure within the fioatdchambeii It will be understood that under such conditions air port is and re- -mains open and that thegrooves form a communication between the supply line and the atmosphere. t is to be understood that the vacuum breaking feature is a definite part of this invention but is omitted-in the preferred form of the invention.

Itwill further be appreciated that except during thosetimes when the device is being-positively supplied with liquid through the normal inlet port the float and bottom disc are gravita- .tionally positioned so as effectively to close such inlet port and to maintain the air port open, thus ensuring that float chamber ii-be under atmos pheric pressure conditions; Since, as previously stated, the device is so positioned with reference to the. associated fixture that liquid cannot re-' turn .tothe device by gratity, and since the device so functions as-to prevent significantly negative- (less thanatmospheric) pressures from arising within float chamber it is not possible for liuuid toreturn from the fixture to the device;

consequently, back flow from such fixture is pre-' cluded and contamination of the supply line is rendered impossible.

In ordinary use, due to the fact that the device is disposed on the discharge or outlet side ofa valve or the-like as already mentioned, it will be apparent that fluid will pass through the hollow I swivel 22, through the inlet opening H, the passage i5 and the opening 14, and under normal conditions will cause the float assembly to rise due to the jet action and buoying 'eiiect of the incoming fluid until the float assembly reaches anequilibrium position, usually in uppermost po sition, closing air .port 35. Under these 'condi-' tions, the fluid then passes through the outlet openings 53 and through the outlet extension 55 to the fluid-carrying line or other suitable conduit.

same fall withinthe appended claims. For example, Iam not limitedto the use of a bottom less 'float or a float of the particular character above described as i may equallywell use a capsule-shaped float 13'! or light gauge'metal, with a suitable bottom disc subjacent thereto or integral therewith; The bottom of the float itself in f such case,-in eiie'ct, acts" to close the opening [4' when the float is in'its lowermost position. In

I "such case-also the capsule-shaped floatwill close "or'seal the opening ,Orpair port 35" in can 21' by "rising against it,- the opening orpo'rt' being pro? titled with annular" rubber-seat-f i3"' for this,

purpose. Such c'onstructionis' illustrated in Fig.

The open-ended type of iioatis'preferred,

however, as I haveidlscover'ed that the same has definiteadvantages- I For example, such a float may as constructed "with a very lighti.( thin)"- section'wlthout danger of collapse even underrelatively-high' operating-pressures since the external and'internalpressures are always balanced.

Furthe'rmore; permanent waterlogging is eliminated such as wouldresult when a hollow sealed float. develop-s a-leak, however slight, In the design of floatshown in Figs. dand 7, thecut away portions 3.9 ensurel drainage should liquid gain aofcessto the float cavity.- Such drainage'will occur when no liquid is entering the device, as

when'the inlet vaive in the'supplyline is closed.

in addition, it is to be'understood' that While I.

have illustrated an'embodiment of the invention wherein the water or other liquid o'r fiuidenters laterally and passes out through the bottom, this is also subject to variation the device may equally well accommodateiluid entering from the bottom-and passing out through theside. The device mayfurther be'so varied as tochange the angular relationships between thevarious parts of the body member; that is to say, the inlet and outlet extensions need not.beatrightI-angles to each other; the inlet extension need not be at rightgnglesto the body and the outletexten'sion need not be a straight angle with the body.

.- Other angular relationship's may' be equally Well employed, depending upon the particular instale lation as Well as thespace requirements and limitations of such installation. The, inlet should,

;.member having buoyancy characteristics such as Thus, during the ex stence of normal or" predetermined conditions within the float chamher the float assembly closes off'the communication of the float chamber with the external'atmosphere via the cap assembly, and thus, in effeet, the device of the present invention permits normal operation of the fluid line substantially as if the present device were not interposed therein.

It is to be understood that the foregoing is presented as exemplary or illustrative and not as limitative or restrictive, and I may, therefore, make additions, omissions, substitutions andalterations in the device without departing from to effect a primary and efiective seal and to ensure complete freedom of leakage of liquid through an air port under all possible conditions of positive liquid supply to the device."

Having thus described my invention, what I I claim as new and desire to secure by Letters Patent'is: V 1 1. A device for preventin back fiow in aliquid-carrying line which comprises a body portion containing a chamber having inlet and out-[L let openings communicating therewith and having-a port to the atmosphere and control members in said chamber capable of gravitational movement to inlet obstructing position under "the scope andprinciple hereof so long as the closing position.

face of which said float is adapted to rest, said float being provided with port sealing means innon-buoyant conditions and to port closing po- ,sition under buoyant flow conditions, said control members including a hollow cylindrical float and a disc disposed entirely below said float andon the annular marginal portion ofthe upper surcluding a seat washer and guide means for en- 7 suring movement of the seat'washer to its port 2. A device for pifeventing back-flow in a liqold-carrying line which comprises a hollow cylindrical body portion vprovided with a bottom having' a central inlet opening andoircumferentially spaced outlet openings, a ported cap assembly 'on the upper end of said body portion, control members in said chamber in the form of a buoyancy-actuated double-acting checkvalve capable of gravitational movement to inlet-obstructing position under non-buoyant conditions and rising movement to port closing position under buoyant flow conditions, said control members including a hollow cylindrical bottomless float made of non-metallic material and having an external diameter only slightly less than the internal diameter of said body portion, a-disc of non-metallic material having a diameter substantially equal to the external diameter of said float and son the annular marginal portion of which said float is adapted to rest, said disc having a depend ing annular skirt forming with the underside of said disc an arrangement sensitive tobuoyancy cular boss surrounding said inlet opening and rising above bottom of said body portion to provide a raised annular inlet seat, a non-metallic ,vlded with a depending annular skirt near the i therein.

' dischaving a diameter only slightly'lessuthan the internal diameter of said body portion and provided with a depending annular skirt near 7 the periphery thereof, said disc being adapted to rest on the'raised inlet seat aforesaid when said disc is in its lowermost position, a hollow non- .metallic cylindrical float substantially equal in its external diameter to the diameter of said disc and disposed above said discand adapted to rest upon the annular marginal portion of the upper surface thereof, the top of said float being closed, a ported closure for the top of said body portion and a seat washer on the top of said float adapted to close said port when said floatis in its ,1

permost position. a A

l. A device for preventing back flow in a liquid carrying line which'rcomprises a hollow cy lindrical body portion having a bottom provided with a central circular inlet opening and circumferentially spaced outlet openings, a hollow circular boss surrounding said inlet opening and rising above bottom of said body portion to provide a raisedannular inlet seat, a non-metallic disc having a diameter only slightly less than the internal diameter-of said body portion and properiphery thereof, said disc being adapted to rest on the, raised inlet seat aforesaid when said disc is in its lowermost position, a hollow non-metallic cylindrical float substantially equal in its external diameter to the diameter of said disc and disposed above said disc and adapted to rest upon the annular marginal portion of the upper surface thereof, the top of said float being'closed, a ported closure for the top of said body portion and a seat washer on the top of said float adapted to close said ort when said float is in its uppermost position, said float and disc being, providcd-with vertical circumferentially spaced ribs and the said float and disc having a combined vertical extent less than the said body portion whereby said float and disc are capable of upward and downward vertical movement in said body portion in response to buoyancy conditions CLEMENS W. HOLTMAN. i 

